Improved mode of constructing



UNITED STATES ATENT Prion.,

JOHN DUBOIS, OF WILLIATWISPORT, PENNSYLVANIA.l

Specification forming part of Letters Patent No. 36,606, dated October 7, 1862.

To all whom it may concern..-

Be it known that l, JOHN DUBOIS, of Williamsport, in the county of Lycoming and State of Pennsylvania, have invented anew and Improved Mode of Constructing, Setting, Removing, and Replacing Bridges; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming part of this specification, in which- Figure l is a vertical longitudinal section of my invention as employed in the construction of a bridge on a sheet of water or river. Fig. 2 is a vertical transverse section of the same as employed in adjusting one side frame of a bridge from a horizontal to a vertical position after it has been constructed on a fioating foundation. Fig. 3 is a side elevation of my invention as employed in setting a bridge ou its piers or removing it therefrom.

Similar letters of reference in the several figures indicate corresponding parts.

In the ordinary way of building and sett-lng bridges the frames, flooring, and other parts require to be erected on the spot where the bridge is to be located. This practice subjects the bridge to great danger of being carried away with sudden freshets,or from other causes, before it is linished,or but partly erected. There is also much inconvenience experienced in the removal and replacement of any section of the bridge by the ordinary methods, it being necessary to take down andremove the heavy portions piece by piece, and in replacing or renewing the portions thus removed the same slow process must be pursued. I

lWIy invention is designed to obviate the above-mentioned difficulties, it allowing of the whole span of the bridge being constructed at once, then serving to carry it to the piers for its support, and answering asa means for `setting it upon the piers; or in case of necessity of removal of the whole span of the bridge or a section thereofand a replacement of the portion removed, it answering those purposes, and that, too, without requiring the pieces of the bridge to be separated.

To enable others skilled in the art to make and use my invention, I will proceed to de# To perform with my invention, I first erect water or the surface of a river by driving long piles a a downinto the bed of such waters, and erect a closed angular or other form of roofing on the top ends of the piles, as represented. I next construct a deep or high floating foundation, B, and provide it with a plug-valV.e,O, and fit the same to a vertical inlet-passage, b, formed in the bottom of the water-tight hollow floating foundation B, as represented. The foundation is boxed up from its bottom and corked tight to withina short distance of its closed or substantial top c, orit maybe wholly boxed up, if deemed best. I however prefer to have it open, as at d, so as to offer less resistance to the atmosphere while in use for transporting the bridge-span to its piers. A pump of any approved construction should also be provided on the floating foundationthe same as on shipboardso that it may be readily brought into use when required. The foundation or floating hollow iioor ofthe workshop is now floated in between the piles a a and lashed in a suitable manner thereto. I now commence to construct one frame, s, of the bridge-span on top of the foundation. This done, I fasten the loose ends of the strong ropes or chainsc e, suspended from the joists of the work-shop, to the ,top chord or stringer of the side frame of the bridge and open the valve C, so as to let water flow into the hollow foundation until the foundation sinks as low as practicable. The valve is then closed and theside frame checked in the inclined position to which it has been raised. The water is now pumped out and the foundation allowed to assume its original position. The ascent of the foundation slackens the cords e, and the-slack must be taken up by the manager of the shop. The valve is now opened again and thewater allowed to enter until the foundation and the side frame, s, assume the position shown in red outlines. Having'thus made room for the erection of another side frame of the bridgespan, I proceed to construct the same on the foundation, asin the first instance; but before doing so the water which flowed into the foundation is pumped out in the same manner as ships are relieved of their water. The second side frame is adjusted to a vertical position in just the same manner as the first. The two frames being adj usted to the proper distance apart, they are connected together by the iioorbeams and cross-ties.

In practice it may be Well to depend upon the rise and fall of the tides to a considerable extent in the adjustment of the side frames, and in such case the side frames should vbe blocked up the distance that they are left suspended after the first fall of the tide, and so on till they are vertical, or nearly so, when the valve may be opened to effect the full adjustment. The bridgespan being erected or built and the floating foundation unlashed from the piles, the foundation with the bridgespan upon it is towed bya steamboat or other means down or up to the piers.

In Fig. 1 the appearance of the bridge-span and the conformation of the top ot` the iioating foundation to the ends of the arches are shown. Vv'hen the foundation and ,the bridge-span arrive in proper position relatively to the piers, the valve C is opened, so as to lower the foundation and set the bridge-span upon and between the piers, as illustrated in Fig. 3. The valve is now closed and the foundation towed .out and down to the Work-shop for use in the erection of another span.

In the setting of the bridgespan upon its piers the rise and fall ofthe tides may also be depended upon to a considerable extent.

It is obvious that the floating foundation which sat the bridge-span upon itspiers may' be used for removing the same in case of damage, and for replacing the repaired span, it

being only necessary to lessen the ballast or quantity of water after the foundation has been towed under the span, in order to lift the span off the piers, and vice versa to replace it there again.

In the erection of a drawer or other part of a bridge which swings on one pier centrally, I shall make the foundation in twolongitudinal sections, so that one section Will pass on one side of the pier and the other section on the opposite side thereof.

My invention will effect an immense reduction in the cost of building bridges,

Vhat I claim as my invention, and desire to secure by Letters Patent, is-

l. Afloat-ing foundation adapted in form and construction and operation, substantially as described, to the purposes herein set forth.

2. The combination of the piles a a and their attachments e, with the floating foundation, so that the side frames ofthe bridge may `be adjusted to a vert-ical position, substantially as set forth.

3. The method, substantially as herein described, of constructing, setting, removing, and replacing a span of a bridge.

Vitness my hand inthe matter of my application for patent on improved mode of constructing, setting, removing, and replacing bridges.

JOHN DUBOIS.

Witnesses:

R. W. FENWICK, DEWITT C. LAWRENOE. 

